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241.
Makoto M. Watanabe Yoshie Takeda Tsutomu Sasa Isao Inouye Shoichiro Suda Tomohiro Sawaguchi Mitsuo Chihara 《Journal of phycology》1987,23(Z2):382-389
A green-colored marine unicell has been grown in unialgal culture and its morphology, chloroplast fine structure, and chlorophyll composition investigated. The organism is typical of dinoflagellates in its shape, flagellation, nucleus, mitochondria, and trichocysts. It is similar to Gymnodinium but possesses fine body scales. Chloroplasts and two kinds of vesicles bounded by double membranes, but no organelles obviously identifiable as nuclei or mitochondria, are associated in ribosome-dense cytoplasm separated by a double membrane from the dinophycean cytoplasm. The chloroplasts are unlike any previously reported for dinoflagellates. Each is enclosed by an envelope consisting of a double membrane. Chloroplast lamellae consist of three appressed thylakoids. Interlamellar pyrenoids are present. Pigment analysis reveals chlorophylls a and b but not chlorophyll c. It seems likely that the organism is an undescribed dinoflagellate containing an endosymbiont with chlorophylls a and b and that the reduction of the endosymbiont nucleus and mitochondria has permitted a more initmate symbiosis. 相似文献
242.
Transient electric birefringence of poly(L -α,γ-diaminobutyric acid hydrochloride) in methanol/water mixtures has been measured over a wide range of field strengths and solvent compositions and at different polymer concentrations and temperatures. The molar ellipticity at 222 nm and the specific Kerr constant underwent an abrupt change between 75 and 80 vol % methanol at 25°C, accompanied by a solvent-induced helix–coil transition. Anomalous birefringence transients were observed between 78 and 80 vol% methanol above threshold field strengths. The double logarithmic plots of the steady-state specific birefringence versus the square of field strength for different solvent compositions and polymer concentrations could be superimposed by shifting them horizontally along the abscissa and vertically along the ordinate except for the range where anomalous transients were observed. The threshold field strength could be estimated from the point at which a downward deviation occurred. It increased with increasing polymer concentration and with increasing methanol content on the verge of the transition region. The results were interpreted as indicating that a conformational change from the charged helix to the charged coil is induced by high fields in this system, as in the case of poly(L -lysine hydrobromide) in methanol/water mixtures. 相似文献
243.
Sachiko Yasuda Masahiro Iwasaki Shin-ichi Oka Satoshi Naganawa Tadashi Nakasone Mitsuo Honda Tetsutaro Sata Asato Kojima Syunji Matsuda Toshitada Takemori Yasuko Tsunetsugu-Yokota 《Microbiology and immunology》1998,42(4):305-311
Secretory immunoglobulin A (IgA) is known to play an important role in the mucosal defense against a variety of pathogens. Although the role of IgA antibodies during sexual transmission of HIV is not clear, HIV-specific IgA antibodies have been detected in various mucosal secretions of HIV-infected individuals. Using a monoclonal antibody against human IgA, we established an ELISA system to detect anti-HIV p24 IgA antibodies in sera and saliva. We have analyzed the levels of anti-HIV p24 IgG and IgA antibodies in sera and saliva of 107 and 119 adults, respectively, with HIV infection at different clinical stages, and in the sera of 13 infants born to HIV-infected mothers. The level of anti-HIV p24 IgA antibodies was lower in sera and higher in saliva as compared to that of anti-HIV p24 IgG antibodies. Where the percentage of HIV-specific serum antibody-positive cases decreased with disease progression, that of saliva antibody-positive cases increased in AIDS patients. Among the 13 infants born to HIV-infected mothers, 7 infants were HIV-p24-specific serum IgA positive. These sera were negative for anti-HIV p24 secretory IgA, suggesting that some infants develop their own immune responses against HIV infection. Thus, the detection of HIV-specific IgA antibodies, especially in saliva, could be a simple and reliable test for the diagnosis of HIV infection. 相似文献
244.
Analysis of Ribosomes from Viomycin-Sensitive and -Resistant Strains of Mycobacterium smegmatis 总被引:6,自引:1,他引:5 下载免费PDF全文
Viomycin-resistant strains were isolated from Mycobacterium smegmatis. Ribosomes were isolated and tested for drug resistance in subcellular systems containing poly(U) as messenger ribonucleic acid. Resistance to viomycin in these strains was due to altered ribosomes. Further analysis showed that viomycin resistance of two mutants with low level resistance (20 mug/ml) was due to altered 30S ribosomal subunits. Another mutant that was highly resistant to viomycin (1 mg/ml), however, had altered 50S ribosomal subunits. 相似文献
245.
Wakamatsu Kunimitsu; Ikehara Norikatsu; Nishimura Mitsuo 《Plant & cell physiology》1974,15(4):601-610
The light-induced absorbance change at 515 nm, light-inducedhydrogen ion uptake and ATP formation were compared in chloroplastsand different types of sonicated subchloroplast particles. Noparallel relationship among the activities for ATP formation,hydrogen ion uptake and the 515-nm change was observed in differenttypes of preparations. NH4Cl inhibited ATP formation in chloroplastsbut had little effect on subchloroplast particles. In contrast,the light-induced hydrogen ion uptake was inhibited by NH4Clin a similar manner. Tetraphenylboron (TPB), at 1 µM, inhibited ATP formationby about 30% in both chloroplasts and subchloroplast particles.In the presence of TPB, ATP formation in chloroplasts was stronglyinhibited by NHC4Cl, but in subchloroplast particles the additionalinhibitory effect of NH4Cl was small. A synergistic inhibitionof photophosphorylation by valinomycin plus NH4Cl was much clearer.Although acceleration of the recovery of the 515-nm change byNH4Cl or valinomycin was moderate, the 515-nm change virtuallydisappeared when NH4Cl and valinomycin were added simultaneously. Although the membrane potential has a major role as the principaldriving force for ATP formation in subchloroplast particles,the simultaneous abolishment of the pH gradient and membranepotential may be required to uncouple ATP formation.
1Present address: Fukuoka Women's University, Kasumigaoka, Fukuoka813, Japan.
2Present address: Ryukyu University, Naha, Okinawa 903, Japan. (Received February 5, 1974; ) 相似文献
246.
Washing spinach chloroplasts with high-concentration Tris-saltbuffers induced various types of anion-dependent changes inthe electron flow and photophosphorylation in chloroplasts. Tris-HCl buffer caused enhancement of NADP photoreduction andinhibition of phosphorylation. Tris-HNO3 buffer, on the otherhand, caused inhibition of both electron flow and phosphorylationand decreased trypsin-activated Ca2+-dependent ATPase activity.Tris-H2SO4 and Tris-H3PO4 buffers, however, had no effect onthe rates of electron flow and photophosphorylation. Determination of the presence of the coupling factor (as measuredby ATPase activity) revealed a normal enzyme activity levelin chloroplasts washed with Tris-HCl or Tris-H2SO4 buffer. Removalof the coupling factor by EDTA from chloroplasts washed withTris salts inhibited phosphorylation severely. Phosphorylationactivity could be partially restored by reconstitution withthe coupling factor in die presence of Mg2+. In addition to their different effects on electron flow, Tris-HCland Tris-HNO3 induced a marked decrease in phosphorylative activityitself. The much decreased rate of phosphorylation can be explainedby the release of the coupling factor and by damage to the high-energystate generating mechanism by Tris-HNO3-washing and by modificationof the coupling factor in the case of Tris-HCl-washing.
1Present address: Biology Department, College of Science andEngineering, Ryukyu University, Naha, Okinawa. Japan. (Received June 27, 1972; ) 相似文献
247.
Matthew A. Caporizzo Claire E. Fishman Osamu Sato Ryan M. Jamiolkowski Mitsuo Ikebe Yale E. Goldman 《Biophysical journal》2018,114(6):1400-1410
Myosin X is an unconventional actin-based molecular motor involved in filopodial formation, microtubule-actin filament interaction, and cell migration. Myosin X is an important component of filopodia regulation, localizing to tips of growing filopodia by an unclear targeting mechanism. The native α-helical dimerization domain of myosin X is thought to associate with antiparallel polarity of the two amino acid chains, making myosin X the only myosin that is currently considered to form antiparallel dimers. This study aims to determine if antiparallel dimerization of myosin X imparts selectivity toward actin bundles by comparing the motility of parallel and antiparallel dimers of myosin X on single and fascin-bundled actin filaments. Antiparallel myosin X dimers exhibit selective processivity on fascin-bundled actin and are only weakly processive on single actin filaments below saturating [ATP]. Artificial forced parallel dimers of myosin X are robustly processive on both single and bundled actin, exhibiting no selectivity. To determine the relationship between gating of the reaction steps and observed differences in motility, a mathematical model was developed to correlate the parameters of motility with the biochemical and mechanical kinetics of the dimer. Results from the model, constrained by experimental data, suggest that the probability of binding forward, toward the barbed end of the actin filament, is lower in antiparallel myosin X on single actin filaments compared to fascin-actin bundles and compared to constructs of myosin X with parallel dimerization. 相似文献
248.
A kidney injury molecule‐1 (Kim‐1) gene reporter in a mouse artificial chromosome: the responsiveness to cisplatin toxicity in immortalized mouse kidney S3 cells 下载免费PDF全文
249.
250.
Complex‐I Alteration and Enhanced Mitochondrial Fusion Are Associated With Prostate Cancer Progression 下载免费PDF全文